Hear sonic booms by slowing down?

[xsouthpawed]

Hi, I'm learning about sonic booms right now in Physics (high school). And I was wondering if it is possible for a pilot to hear his sonic boom by first going faster than the speed of sound (breaking the sound barrier) and then slowing down (letting the waves rush past him)? I asked my physics teacher and he said he didn't know the definite answer.

Thanks in advance!

P.S. I tried searching around (this forum and the rest of the internet) and couldn't find the answer, but I have a feeling that the answer is no.
P.P.S. Sorry if I posted in the wrong forum. This isn't homework, I promise!

 

[willem2]

The plane is at the tip of the cone of the sonic boom, so just slowing down to below sound speed won't help, because the plane will be inside the cone, and the sonic boom will already be past. If the plane turns sharply, still going faster than the speed of sound, it should be able to get in front of the shockwave, and then slow down to let it pass.

 

[xsouthpawed]

The plane is at the tip of the cone of the sonic boom, so just slowing down to below sound speed won't help, because the plane will be inside the cone, and the sonic boom will already be past. If the plane turns sharply, still going faster than the speed of sound, it should be able to get in front of the shockwave, and then slow down to let it pass.

Does this mean that it is possible to hear the sonic boom? (by letting it pass after turning)

 

[Cleonis]

Hi, I'm learning about sonic booms right now in Physics (high school). And I was wondering if it is possible for a pilot to hear his sonic boom by first going faster than the speed of sound (breaking the sound barrier) and then slowing down (letting the waves rush past him)?

A similar question would be: can you drive a boat in such a way that at some point the boat is rocked by its own bow wave?

The bow wave trails the boat in a V-shaped pattern, with the boat at the point of the V. As long as the boat stays on a straight line it cannot outrun its own bow wave. If the boat increases velocity the angle of the V becomes sharper, but as long as you keep a straight line there is no such thing as outrunning your own bow wave.

What you can do, of course, is make a sharp turn, and then decelerate. That way you allow yourself to be overtaken by the bow wave that now comes up from behind.In the case of the shockwave that is trailing an aircraft flying faster than the speed of sound:
I don't know whether it's possible to make a sharp enough turn.

As the shockwave wavefront propagates it becomes spread out over a larger volume of air, and the intensity decreases proportionally.
When an aircraft flies at supersonic speed it takes a lot of time to make a turn and then drop below the speed of sound. The wavefront will eventually overtake the aircraft, but by that time the wavefront may have spread out so much that it's no longer a boom.

I'm reminded now of the Mythbusters episode where a supersonic capable aircraft made a number of passes (over a desert area), each time at a lower altitude. To make a sharp, explosion-like sonic boom reach ground level the jet had to fly pretty low.

If I hazard a guess I think making a turn and slowing down will take too much time. Taking more time means flying a longer distance. I guestimate that when the wavefront eventually overtakes the remaining intensity of the sonic boom is no longer enough to be heard above the jet noise of the jet aircraft itself.

 

[rcgldr]

Another alternative would be to simply u-turn back into the sonic boom. Note that a shock wave is not a sine wave, the lowest pressure is zero, but there's no limit to the highest pressure. A shock wave transitions into a normal sound wave, which is heard as a sonic boom. An actual shock wave is more like a crack. An example of this can be heard in the second part of this video, where a F-14 makes a close super-sonic flyby:

http://rcgldr.net/real/f14flyby.wmv